ci: update test workflow to send coverage to coveralls

Author: mthh

.github/workflows/ci-tests.yml

@@ -55,6 +55,28 @@ jobs:
       run: |
         pip install -e .
         coverage run --source=routingpy --module pytest
-        coverage lcov --include "routingpy/*"
+        coverage lcov --include "routingpy/*" --output-file=coverage.lcov
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Upload coverage artifact
+      if: matrix.python_version == '3.12'
+      uses: actions/upload-artifact@v4
+      with:
+        name: coverage-lcov
+        path: coverage.lcov
+
+  coveralls:
+    needs: build
+    runs-on: ubuntu-22.04
+    steps:
+      - uses: actions/checkout@v4
+      - name: Download coverage artifact
+        uses: actions/download-artifact@v4
+        with:
+          name: coverage-lcov
+      - name: Send coverage to Coveralls
+        uses: coverallsapp/github-action@v2
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          path-to-lcov: coverage.lcov